I'd just add that with a large number of subscriptions this would be pretty slow. More efficient is to retrieve all data by a single request to the API.
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RocketRNov 17 '12 at 10:48

Thanks Adam. I'm still a little confused. I've added the method into the subscription model and I've removed the GC logic from the controller. In the index view I have <% @subscriptions.each do |subscription| %> and then called <%= subscription.gc_subscription.next_interval_start %>. I get a 404 error though. I've checked that the subscription table has only one resource_id that's valid. Should I have subscription = Subscription.find(id) in the controller?
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dannymccNov 17 '12 at 11:37

I think it might be 404 because I'm not setting my merchant ID.
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dannymccNov 17 '12 at 11:53